Geothermal brine reservoirs exist in many areas of the world and represent a valuable energy resource. Typically, the energy contained in the hot geothermal brine is recovered in a geothermal power plant by flashing the brine to produce steam and then using the steam to activate a turbine connected to an electrical generator.
The geothermal brine presents handling difficulties in the geothermal power plant. For example, geothermal brines, and particularly those from a geothermal resource at a temperature of about 400.degree. F. or more, are rich in silica, which can, by complex chemical reactions involving silica polymerization, come out of solution, forming solid amorphous silica deposits that scale equipment. These deposits are particularly troublesome with equipment designed to extract energy, e.g., flashing vessels and heat exchangers, but the silica in the brine also presents problems in any equipment or piping in which the brine is transported, including the piping for re-injection wells.
Indeed, silica deposition problems can even extend to the formation into which the brine is ultimately re-injected. If the silica substantially deposits soon after re-injection, the end result could be premature plugging of the formation, rendering it a useless or more difficult resource from which to recover geothermal fluids.
Likewise, the acidity of geothermal brines can present problems, in particular, corrosion problems. For example, brines at pH values below about 4.5 typically require expensive alloys for their handling, such as titanium or high nickel alloys. Oftentimes, the problem can be so severe, and the cost to handle the acid brine so expensive, that in many instances the "acid well" is shut in or used only as a re-injection well. Needless to say, such procedures decrease the energy resource base.